The present invention relates to a device for providing a flow of active gas. In particular the invention is directed towards a device used which generates non-thermal plasma for treating an oral region of a human or animal body.
Systems for the generation of non thermal gas plasmas are known and have utility in a number of fields such as industrial, dental, medical, cosmetic and veterinary fields for the treatment of the human or animal body. Non-thermal gas plasma generation can be employed to promote coagulation of blood, cleaning, sterilisation and removal of contaminants from a surface, disinfection, reconnection of tissue and treatment of tissue disorders without causing significant thermal tissue damage.
Hereto, the application of non-thermal plasmas has been confined to controlled environments, such as in industry or clinics, since there is risk associated with the generation of plasmas with high electrical potentials, which if transmitted to a patient can cause injury or fatalities. The use of a plasma in a consumer product has therefore been limited, where controlled use of plasma generation cannot be assured.
Typically, in plasma generation energy is applied to a gas or gas mixture for ionising the molecules or atoms of the gas producing an ionic species, or plasma. Energy is supplied to the gas either by inductive or capacitive coupling. Electrodes are provided for supplying energy to gas in a plasma cell and in order to protect a patient from the high electrical potential of the electrodes, the electrodes have been insulated with a dielectric material. However, such an arrangement has been found to have draw-backs, since the use of a dielectric reduces the effective potential of the electrode and therefore requires a source of higher potential to drive the electrodes. A higher potential source is either more expensive or may be drained more quickly, particularly in a consumer device in which the source is one or more batteries. Further, electrodes having dielectric insulation are driven by alternating current which can pass through the electrode arrangement potentially causing injury to a user.
In the context of this application, the term cold, or non-thermal plasma means that the plasma has a temperature of less than about 40° C. which is a temperature tolerable to a patient without causing injury or discomfort. Such plasmas have only a small proportion of the gas molecules in an ionised state.
In typical generators of non-thermal plasma, the plasma generation cell is remote from an applicator which in use is positioned adjacent to a region to be treated (‘treatment region’). There are several disadvantages to such arrangements. In particular, difficulties may arise in obtaining an adequate concentration of active species at the treatment region as a result of decaying numbers of active species as the gas flows from the remote plasma cell to the treatment region and because the performance of the plasma cell may deteriorate with time.